In recent years, progress is being made in research and development of diverse functional elements which involve the use of an organic semiconductor. One typical example of a functional element is an organic EL element. An organic EL element is a current-driven light-emitting element, and commonly has a pair of electrodes, namely a pixel electrode and a common electrode, and functional layers layered between the pair of electrodes. The functional layers include a light-emitting layer composed of an organic material. Upon application of voltage across the pair of electrodes, holes injected from the pixel electrode to the functional layers recombine with electrons injected from the common electrode to the functional layers. The recombination causes the phenomenon of electroluminescence, which involves emission of light. Given the high visibility of organic EL elements resulting from their self-luminescence, as well as their excellent shock resistance resulting from the fully solid-state structure thereof, more attention is now being given to the application of organic EL elements as a light-emitting element for various organic EL display panels and organic EL display apparatuses or a light source.
Generally, a common electrode of an organic EL display panel is disposed to cover the entire surface of the panel on which organic EL elements are arranged. At the periphery of the panel, the common electrode is connected to a voltage source so that voltage is externally applied to the common electrode. Due to this structure, the central area of the panel is supplied with voltage from the voltage source via an electrical resistance of the common electrode. Therefore, the voltages applied to the light-emitting layer in the central area and in the peripheral area of the panel might vary greatly despite the same voltage supplied from the voltage source, and accordingly the luminance of each organic EL element might differ from each other. To solve this problem, there has been a proposal of the use of, in addition to the common electrode, an auxiliary connector having a lower resistance than the common electrode, and thereby reducing the difference among the voltages applied to the light-emitting layers in the panel (Patent Literature 1).